Electricity is commonly generated at a power station by electromechanical generators, which are typically driven by heat engines fueled by chemical combustion or nuclear fission, or driven by kinetic energy flowing from water or wind. The electricity is generally supplied to end users through transmission grids as an alternating current signal. The transmission grids may include a network of power stations, transmission circuits, substations, and the like.
The generated electricity is typically stepped-up in voltage using, for example, generating step-up transformers, before supplying the electricity to a transmission system. Stepping up the voltage improves transmission efficiency by reducing the electrical current flowing in the transmission system conductors, while keeping the power transmitted nearly equal to the power input. The stepped-up voltage electricity is then transmitted through the transmission system to a distribution system, which distributes the electricity to end users. The distribution system may include a network that carries electricity from the transmission system and delivering it to end users. Typically, the network may include medium-voltage (for example, less than 69 kV) power lines, electrical substations, transformers, low-voltage (for example, less than 1 kV) distribution wiring, electric meters, and the like.
The following, the entirety of each of which is herein incorporated by reference, describe subject matter related to power generation or distribution: Engineering Optimization Methods and Applications, First Edition, G. V. Reklaitis, A. Ravindran, K. M. Ragsdell, John Wiley and Sons, 1983; Estimating Methodology for a Large Regional Application of Conservation Voltage Reduction, J. G. De Steese, S. B. Merrick, B. W. Kennedy, IEEE Transactions on PowERSs, 1990; Power Distribution Planning Reference Book, Second Edition, H. Lee Willis, 2004; Implementation of Conservation Voltage Reduction at Commonwealth Edison, IEEE Transactions on PowERSs, D. Kirshner, 1990; Conservation Voltage Reduction at Northeast Utilities, D. M. Lauria, IEEE, 1987; Green Circuit Field Demonstrations, EPRI, Palo Alto, Calif., 2009, Report 1016520; Evaluation of Conservation Voltage Reduction (CVR) on a National Level, PNNL-19596, Prepared for the U.S. Department of Energy under Contract DE-AC05-76RL01830, Pacific Northwest National Lab, July 2010; Utility Distribution System Efficiency Initiative (DEI) Phase 1, Final Market Progress Evaluation Report, No 3, E08-192 (July 2008) E08-192; Simplified Voltage Optimization (VO) Measurement and Verification Protocol, Simplified VO M&V Protocol Version 1.0, May 4, 2010; MINITAB Handbook, Updated for Release 14, fifth edition, Barbara Ryan, Brian Joiner, Jonathan Cryer, Brooks/Cole-Thomson, 2005; Minitab Software, http://www.minitab.com/en-US/products/minitab/ Statistical Software provided by Minitab Corporation.
Further, U.S. patent application 61/176,398, filed on May 7, 2009 and U.S. publication 2013/0030591 entitled VOLTAGE CONSERVATION USING ADVANCED METERING INFRASTRUCTURE AND SUBSTATION CENTRALIZED VOLTAGE CONTROL, the entirety of which is herein incorporated by reference, describe a voltage control and energy conservation system for an electric power transmission and distribution grid configured to supply electric power to a plurality of user locations. U.S. patent application 61/800,396, filed on Mar. 15, 2013, and U.S. patent application Ser. No. 14/193,552, filed Feb. 28, 2014, entitled MAXIMIZING OF ENERGY DELIVERY SYSTEM DELIVERY SYSTEM COMPATIBILITY WITH VOLTAGE OPTIMIZATION USING AMI-BASED DATA CONTROL AND ANALYSIS, the entirety of each are herein incorporated by reference, describe a voltage control system for making the voltage optimization system for an electrical delivery system compatible with high variation distributed generation and loads. U.S. patent application 61/789,085, filed on Mar. 15, 2013, and U.S. patent application Ser. No. 14/193,190, filed Feb. 28, 2014, entitled ELECTRIC POWER SYSTEM CONTROL WITH MEASUREMENT OF ENERGY DEMAND AND ENERGY EFFICIENCY USING T-DISTRIBUTIONS, the entirety of each are herein incorporated by reference, describe measuring the effects of optimizing voltage, conserving energy, and reducing demand using t distributions. U.S. patent application 61/800,028, filed on Mar. 15, 2013, and U.S. patent application Ser. No. 14/193,770, filed Feb. 28, 2014, entitled MANAGEMENT OF ENERGY DEMAND AND ENERGY EFFICIENCY SAVINGS FROM VOLTAGE OPTIMIZATION ON ELECTRIC POWER SYSTEMS USING AMI-BASED DATA ANALYSIS, the entirety of each are herein incorporated by reference, describe improved controlling of the voltage on distribution circuits with respect to optimizing voltage, conserving energy, reducing demand and improving reliability. U.S. patent application 61/794,623, filed on Mar. 15, 2013, and U.S. patent application Ser. No. 14/193,872, filed Feb. 28, 2014, entitled ELECTRIC POWER SYSTEM CONTROL WITH PLANNING OF ENERGY DEMAND AND ENERGY EFFICIENCY USING AMI-BASED DATA ANALYSIS, the entirety of each are herein incorporated by reference, describe improved control of an electric power system including planning the distribution circuits with respect to optimizing voltage, conserving energy, and reducing demand.
Electrical loads consume real power to perform work. Electrical power distribution and load systems may include inductive and/or capacitive loads that can temporarily store electrical power, which does not contribute to work. This stored power may be eventually returned to the electrical power distribution system as reactive power, often out of phase with the voltage, causing a difference between the current phase and the voltage phase. Volt-ampere reactive (VAR) is a unit of this reactive power. Other types of loads may also cause a shift in the current phase with respective to the voltage phase. The vector sum of the real power and the reactive power is the apparent power. The ratio of the real power to the apparent power is the power factor (PF) (dimensionless)
Capacitive loads generally cause the system current phase to be ahead (“lead”) the system voltage phase. Inductive loads generally cause the system current phase to be behind (“lag”) the system voltage phase. Thus, when accounting for the phase angle, power factor can be expressed as a number less than or equal to 1, and as either lagging or leading. The power factor decreases as the system becomes more lagging or more leading.
Poor system performance can occur when an electrical system is drawing too many VARs (i.e., the system is lagging too much), or when a system is generating too many VARs (i.e., the system is leading too much). By drawing or generating too many VARs, the magnitude of the vector sum of the real power the reactive power increases. Adding and/or subtracting capacitive or inductive loads can correct a leading or lagging power factor by counteracting the effects of other capacitive or inductive loads and thus decreasing the amount of reactive power in a system. As the magnitude of reactive power decreases, the ratio of real power to the apparent power increases (and thus the power factor approaches 1). However, the known devices designed to control power factor add and/or subtract loads independently, and only take into account local conditions. Therefore, by correcting to local VAR conditions, a system may be corrected too far in the opposite direction or add and/or subtract loads that are not optimal.